Thanks a lot mate! I suspected the same and i found the "Seiko" branding missing as an anomaly i might be wrong on this but i've never even seen an actus without Seiko written on it. I have some more watches to verify as well let me post the pics here!

Now i do realize Seiko 5's were equipped with 7S26a movement in the past as the back shows but the dial again is that of the Seiko 5 military watch but the casing is way to shiny even if we consider that they changed the Nato strap for some reason

I will just say one possibility is that the watch is "correct" but that the case had been "buffed"/polished & thus may not look the same as it should.

With the older Seikos, it is common to have "frankens" [legitimate Seiko parts from different models all thrown together] and restorations where 3rd party replacement parts have been added to replace original parts and "mods" where the owner wished for a different look from "factory spec".